Multiple pure tone elimination strut assembly

Abstract

An acoustic noise elimination assembly having a capability for disrupting the continuity of fields of sound pressures forwardly projected from fans or rotors of a type commonly found in the fan or compressor first stage for air-breathing engines, when operating at tip speeds in the supersonic range. The assembly incudes a tubular cowl 12 defining a duct for delivering an airstream axially into the intake for a jet engine E and a sound barrier 14, defined by a plurality of intersecting flat plates or struts 14a-14d having a line of intersection coincident with a longitudinal axis of the tubular cowl, which serves to disrupt the continuity of rotating fields of multiple pure tonal components of noise.

What is claimed is: 
     
       1. A pure-tone elimination assembly adapted to be mounted upstream from the air intake for a jet engine characterized by a bladed rotor having operational tip speeds in the supersonic range, whereby the engine is further characterized by a forwardly projected rotating field of multiple pure-tone noise at operational speeds, comprising: A. a tubular cowl defining a duct for delivering an airstream axially into the air intake for said engine; and   B. a plurality of struts for disrupting the continuity of a rotating field of multiple pure-tone components of noise comprising a plurality of flat, plate-like members arranged in mutually intersecting planes and having a line of intersection coincident with the longitudinal axis of said cowl.   
     
     
       2. A pure-tone sound elimination device as defined in claim 1 wherein said plurality of struts comprise at least four flat, plate-like members arranged in an intersecting configuration conforming to a cruciform and having an axis of intersection coincident with the longitudinal axis of said cowl. 
     
     
       3. A pure-tone sound elimination assembly, as defined in claim 2 having a dimension along said axis of intersection at least as great as the diametric dimension of said rotor.